Textile treatment



Patented Feb. 16, 1943 TEXTILE TREAiTMEN T William J. Burke, Robert w. Maxwell, one Paul s. Pinkney, Wilmington, Del., assignors to E. L

du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application November 8, 1940,

Serial No. 364,850

14 Claims.

This invention relates to the treatment with formaldehyde of textile materials whichare reactive thereto. More particularly, it relates to a process for reacting a textile material with formaldehyde without objectionably altering the uniformly colored; however, those heated in tris(p-hydroxyethyl)amlne are more deeply colored than that heated in mineral oil. Photomicrographs of cross-sections of dyed fibers show that the fibers heated in tris(p-hydroxyethyl)- dye amnity of th t til at ri l, amine are penetrated more deeply by the dye than t has long b known t react t til me,- are those heated in mineral oil. This shows that terials with formaldehyde. Such reaction has a surface layer of the fibers heated in trisqsbeen carried out for the purpose of increasing the yd yethyl) a e been modlfied s y strength 01 textiles or to improve their resilience, o reaction with o a d yde n has a Similar crease resistance, crush resistance, crimp retensurface layer of the fibers he in mineral 01L tion, resistance to shrinking, and to reduce the e fi c s o t S p are modified dry and wet elongation and the extent to which substantially to an eq l extent in both casessuch materials are swelled by water.

Many of these previously known processes are Example H o j i na le in th t they al er he dye filnit Five skeins of the yarn described in Example I of the textile meterifllwere impregnated with a water solution containt s, e ef e, an object f the prese t invening 13% of formaldehyde and 0.5% of ammonium tion to provide a process for reacting a textile machloride, centrifuged and dried t room temperaterial with formaldehyde without objectionably 2o t beforeefen, Th al keins were heated altering t y affinity o t teXtile materialby immersion for 5 minutes in baths consisting re- Other objects of the invention will appear spectively of: 1 hereinafter 1 Aniline having a temperature of 135-138 c The objects of this invention may be accomo 2. Pyridine having a temperature of 115 C. plished, in general, by impregnating a formalde- 3 hydrox eth D amine having a tempem hydeei'eactiige textiilehg naterial with the desired 51 3,, quant ty-"of orma de do together wi h an acidreacting catalyst, drying the impregnated mateii i xylene containing 10% of dlmethyl' rial and heating the same to the desired reaction temperature by immersion in a hot organic liq- 3o 4% 0150' uid bath having a basic reaction, preferably a d m u y bath-comprising a sufficient quantity of a basic A11 five samples showed mark d improvement hi nitrogen-containing material that the bath as a crease resistance upon dyeing with a direct Whole is basic in reaction dyestuff showed less loss in dye aiflnity than sam- The following examples illustrate in great 35 ples given comparable crease resistance by treattail the preferred methods of carrying out the ment with formaldehyde followed by curing in process of this invention. It is to be undermineral stood, however. that the present invention is not In accordance ith the present invention, any limited to the specific details set forth therein. f rma1dehyde-react1ve t t material, ti

Emmple I larly a formaldehyde-reactive cellulosic textile material, when impregnated with formaldehyde Skeins of the newly developed crimped viscose and an acid reacting catalyst, dried, and then rayon yarn described and claimed in United heated by immersion in a hot organic liquid bath States application, Serial No. 180,976, filed De-. having a basic reaction, preferably a bath comcember 21, 1937, by William Hale Charch and prising a sufficient quantity of a basic nitrogen- William Frederick Underwood, are impregnated containing material to render the bath basic in with a water solution containing 2% of formalreaction, will produce a uniformly resilient, dehyde and 0.2% of ammonium chloride. The crush resistant and crease resistant product skeins of yarn are then centrifuged and dried at having improved dyeing characteristics. It is room temperature. One of said skeins is imconsidered that the improved dyeing charactermers'ed in mineral oil at 150 C. for 5 minutes istics result from the fact that the acid reacting and the other is immersed in trisQS-hydroxycatalyst reacts with the basic reacting bath on ethyl) -amine at 150 C. for 5 minutes. Both the surface of the fibers and, therefore, the surskeins are then thoroughly washed to remove all face of the fibers remain substantially unmoditraces of bath liquid. Both skeins show marked fied. The cores of the fibers, however, are reimprovement in resilience, crease resistance and acted with formaldehyde to substantially the wet strength. Thedegreeofimprovement is about same extent as if the yarn were heated in an the same in both cases. Samples of each skein inert bath; that is, one which is not basic in are dyed with Pontamine Sky Blue 6 BX (Rowe character. Color Index No. 518). Both sets of samples are As a formaldehyde-reactive textile material,

the present invention contemplates the treatment of filaments, yarn, fabrics and the like comprising regenerated cellulose, regenerated protein materials, and low substituted cellulose esters and ethers; i. e., cellulose esters and ethers having at least one unsubstituted hydroxyl group.

The present invention is operative in the treatment of all textile materials which are at all reactive to formaldehyde. In the treatment of such textiles as are less reactive than those specifically referred to above, the treating conditions will, of course, be more drastic.

The term textile material" includes fibers in the form of loose staple, yarn, fabric, or finished article and filaments in the form of yarn, fabric, or finished article. The fabrics may be knitted, woven, or felted. They may be special types of fabric such as pile fabrics or crep'e. Viscose rayon fibers may be treated in the gel state either as staple, rope, or yarn.

The term acid-reacting catalyst is intended to include water soluble substances which are acid in reaction, or capable of becoming acid under the conditions of the treatment, or capable of liberating an acid under the conditions of the treatment. Examples are organic carboxylic or sulfonic acids such as oxalic acid, tartaric acid, and benzenesulfonic acid, acid salts of organic acids such as sodium acid tartrate and potassium tetroxalate, mineral acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, acid salts of mineral acids such as sodium bisulfate and dihydrogen sodium phosphate, and salts of strong acids with weak bases which dissociate in water solution to give an acid reaction such as ammonium thiocyanate, ammonium chloride, ammonium bromide, ammonium iodide, ammonium sulfate, hydroxylamine hydrochloride, ferric chloride, calcium chloride, aluminum chloride, etc. The catalyst chosen in any particular case will be the one which is sufllciently powerful to effect the degree of chemical reaction desired between the textile material and the formaldehyde. Because of its cheapness and effectiveness, ammonium chloride is the catalyst which is preferred in the exercise of this invention.

As liquids suitable for use as components of the heating bath in the process of the present invention, there may be used any organic liquid boiling above 70 C. and preferably above 100 0., which bath is basic in reaction. The bath may, of course, be composed of a neutral liquid material which is capable of dissolving substantial quantities of basic materials without reacting therewith, so that the bath as a whole is basic in reaction under the conditions prevailing during the heating step. As examples of suitable liquids which are basic in reaction, the following may be named: Tertiary amines such as tris(fl-hydroxyethyl)amine, triallylamine, tris- (,B-hydroxypropyhamine, N-butyl bis(B-hydroxyethyl) amine, diethylaminoethanol, phenylmorpholine, pyridine, dimethylaniline, N-phenyl As examples of suitable liquids which are ccpable of dissolving substantial quantities of basic materials the following may be named: Hydrocarbons such as benzene, toluene, xylene, .kerosene, mineral oil, high boiling benzine, triisobutylene, etc; alcohols such as glycerol, ethylene glycol, butanols, octanols, etc.; hydroxy ethers such as Cellosolves and Carbiiols'k ethers such as diisobutyl ether, bis(methoxyethoxyethyl) ether, bis(ethoxyethyl)ether, dioxan, etc. Of course, ethers or other materials which are solvents for cellulose ethers cannot be used as constituents of baths for heating textile materials composed of cellulose ethers.

Basic materials suitable for use as solutes to render the liquid bath basic in reaction may be organic or inorganic. The one to be used with any particular liquid will, of course, depend on its solubility in that liquid. Strong inorganic bases such as sodium and potassium hydroxides, sodamide, and sodium alooholates need be soluble to an extent of at least 0.5%. Weaker inorganic bases should be more soluble, preferably to an extent of at least 2%, so that an effective concentration can be built up. Other basic materials suitable for use as bath baslfying agents include ammonia, urea, butyl urea, thiourea, cyanamide, guanidine, hydrazine, hydroxylamine, etc.

The formaldehyde treating solution may contain desired modifying agents which will improve the resulting product, as long as the modifying agent does not interfere with the reaction between the formaldehyde and the textile material. For example, long chain agents such as glycerol monostearate or sulfonated castor oil may be added to the formaldehyde solution to improve hand and feel of the textile material. However, when such a. long chain agent is used and the liquid heating medium used is a solvent for it, it is preferable to saturate the liquid heating medium with the long chain agent so that the agent will be retained by the textile material and not dissolved out by the heating medium.

The concentration of formaldehyde to be used in the treating solution varies, of course, with the material under treatment, the nature and concentration of the catalyst, the nature and concentration of modifying agents, the conditions of drying and heating, and the effect desired. For example, for creaseprooflng viscose rayon a higher formaldehyde concentration is required than for shrinkproofing the material, other conditions remaining the same. Generally.

. when the drying and heating conditions are more severe, that is when higher temperatures and longer times are employed, less formaldehyde is required. Thus, if the impregnated material is dried at C. rather than at room temperature, less formaldehyde will be required to give the same final effect. Generally, to obtain cornparable effects, less formaldehyde is required when a more strongly acidic catalyst is employed or when a catalyst is used in higher concentrations, than when a more weekly acidic catalyst is employed or when a catalyst is used in lower concentrations. Usually, a concentration of formaldehyde of at least 1% is required to obtain a noticeable effect on cellulosic ma terials. The upper limit is the concentration at which the particular textile material being treated is made too weak or too brittle for use. As a general rule, the formaldehyde concentration should notexceed 20%. With these facts uncommon-accommodamind, one termine the which-will give optimum results under a given set of other conditions. A high diflerentiai in degree of textile modification between the core and the outer surface of the fiber under treatment is favored by using a relatively high concentration of formaldehyde to 20%) in the treating solution and carrying out the reaction at a relatively low temperature, preferably below 110' C.

The catalyst concentration may vary from as low as 0.05% or lower to as high as 1% or higher depending on the potential acidity of the catalyst, the nature of the textile material under treatment, the concentration of formaldehyde employed, the nature and concentration of modifying agents, the drying and heating conditions. and the effect desired. Other conditions remaining the same, an increase in the catalyst concentration or a change from a less to a more strongly acid catalyst results in a greater degree of modification of the textile material. Usually, the selection of the nature and concen tration of the catalyst is a matter of balancing catalyst efllciency against tendering which resuits-from the use of acidic materials on many textile materials, particularly cellulosic materials. By reference to the above examples and the following description one skilled in the art can readily select the proper catalyst and concentration to bring about the desired result.

The treating solution may be applied to the textile material in any of several ways. Staple fibers may be dipped in the solution and squeezed or centrifuged to remove excess solution. Yarn may be passed continuously through the solution or it may be dipped in skein form in the solution and then squeezed or centrifuged to remove excess solution. Flat fabrics may be passed through the solution or the solution may be ap plied from rolls 'or by spraying and the excess may be removed by squeezing between rolls or by vacuum extracting. Articles, as of clothing, may be dipped in the solution or sprayed. Fabrics or articles of clothing may be treated locally by spraying.

The formaldehyde and catalyst may also be applied in other ways. For example, the'textile material may be wet with a solution of the catalyst and then exposed to vapors of formaldehyde, or it may be wet with formaldehyde solution and then exposed to a gaseous catalyst such as hydrochloric acid.

After impregnation with the treating solution the textile material is preferably dried to a water content of about or less before it is subjected to the final heat treatment. This may be carried out in any of several ways. It may be dried in. air or in a heated inert liquid such as a hydrocarbon or ether. If it is air dried, the temperature of drying may range from room terns perature to 150 C. or higher. Drying at high temperatures in air must be carried out with care so that no part of the textile material is heated after it is dry. Uniformity is favored by vigorous circulation of air in the drying chamber and by use of temperatures below 100 0., and preferably below 50 C. Liquid temperatures up to 250 C. or higher may be used. If a temperature below 100' C. is used, it is usually necessary to boil the drying liquid in order to carry out the water. Consequently, for drying at such temperatures liquids boiling below 100 C. are desirable. However, if they boil below about 70 C.. the rate of concentration of formaldehyde thedryingmethodused."whentheairdrying'- dryingwillgenerallybetoolowiorpractical purposes.

The time ofdryingdepends,of oourse,oa

methodisused,the timerequireddependsonthe temperature, circulation of air, and the relative thickness and looseness of the 'material under treatment. -When the hot liquid drying method is used, the time required depends on the nature of the liquid and the temperature used and less on the construction of the material under treat-- ment. In general, with temperatures below 0., the air drying method is more rapid and may require as short a time as 2 minutes. when the material under treatment is in a relatively loose condition so that air will circulate through it freely, air drying hasan advantage over drying in a hot liquid in that the formaldehyde concentration required for a given degree of modification is much lower and the overall period during which the material is held at the higher liquid temperature is shorter, so that the risk of tendering due to the effect of the acid reacting catalyst at high temperatures is less. At higher temperatures theliquid drying method is generally more rapid due to more efficient heat transfer between the moisture and the heating medium. In general, with other conditions remaining constant, an increase in the drying temperature leads to a greater degree of modification of the textile material.

.In order to bring about a reaction between formaldehyde and the textile material within a 3 reasonable time, it is necessary to heat the impregnated and dried material. In this process the heating step is carried out by immersing the textile material in a hot liquid of the nature disclosed above. The temperature of the liquid may be as low as 70 C. or lower, although a much longer heating period is required at such low temperatures. As already pointed out, if a heating temperature below 100 C. is used, that temperature shouldbe the boiling point of the liquid so that water formed by the reaction will be removed eiilcientiy. The temperature of the liquid may range as high as 200 C. or even higher. However, it should be emphasized that at such high temperatures the heating period should be reduced to the neighborhood of 1 minute or less to avoid damaging the textile material. The

heating temperature depends on the amount of formaldehyde used, the nature and amount of catalyst, the nature and amount of modifying agent, the temperature of drying, the time of heating, the effect desired, and the nature of the textile material under treatment. It is common knowledge that some textile materials are more susceptible to damage by heat than are others and so require more careful treatment in any heating process. In general, with other conditions remaining constant, an increase in the temperature of the heating liquid leads to a greater degree of modification of the textile material under treatment.

The heating P riod may be varied from as long as an hour or more at low temperatures, such as 70-80 C. or lower, to a fraction of a second at higher temperatures, such as 200 C. or higher. When the heating is to be carried on over a period of about a minute or longer, it is advantageous to place the textile material in a perforated container which is lowered into the hot liquid bath and then lifted after the desired length of time. When yarn or fabric is to be heated at a higher temperature for' a shorter period of time, it is advantageous to pass the yarn or fabric continuously through the heating bath at a rate depending on the length of bath travel. with other conditions remaining constant, an increase in the heating period leads to a greater degree of modification of the tex-' tile material under treatment.

I From the above descriptions, it will be apparent that the drying step'and the heating step may be combined into one continuous step. The drying liquid may be used for the subsequent heat treatment. Thus, it is sometimes convenlent to prolong the period of immersion in the drying liquid until the reaction between formaldehyde and the textile material has proceeded to the desired point.

After the heating step, it is usually desirable to remove the heating liquid. This may be accomplished simply by washing the textile material with water. Water-insoluble, non-volatile materials may be displaced by a volatile or waterwith formaldehyde, the steps comprising impregsoluble solvent or removed by soaping. It is usually desirable to neutralize any traces of acidic material which may be left in the yarn by washing with a solution of ammonium hydroxide or other mildly alkaline material. The treated material may then be finished in any desired manner such as by application of a softening agent or water repellent agent.

Since it is obvious that many changes and modifications can be made in the above-described details without departing from the nature and spirit of the present invention, it is to be understood that the invention is not to be limited to the said details except as set forth in the following claims.

We claim: e I i 1. In a process for reacing a textilematerial with formaldehyde, the steps comprising impregnating said material with an aqueous solution of formaldehyde and an acid reacting catalyst, dry-' ing said impregnated material, and heating the same to reaction temperature by immersion in a hot organic liquid bath which is basic in reaction. a

2. In a process for reacting a textile material with formaldehyde, the steps comprising impregnating said material with an aqueous solution of formaldehyde and an acid reacting catalyst, drying said impregnating material, and heating the same to reaction temperature by immersion in a hot organic liquid bath comprising a suillcient quantity of a basic nitrogen-containing material that the bath is basic in reaction.

3. In a process for reacting a textile material with formaldehyde, the steps comprising impreghating said material with an aqueous solution of formaldehyde and an acid reacting catalyst, dryingsaid impregnated material, and heating the same to reaction temperature by immersion in a hot organic. liquid bath comprising a sumcient quantity of a basic amino nitrogen containing material that the bath is basic in reaction.

4. In a process for reacting a textile material with formaldehyde, the steps comprising impregnating said material with an aqueous solution of formaldehyde and an acid reacting catalyst, drying said impregnated material, and heating the same to reaction temperature by immersion in a hot organic liquid bath comprising a suflicient nating' said material with an aqueous solution of formaldehyde and an acid reacting catalyst, drying said impregnated material, and heating the same to reaction temperature by immersion in a hot organic liquid bath comprising a suilicient quantity of triethanolamine that the bath is basic in reaction.

6. In a process as defined in claim 1 in which the temperature of the liquid bath is maintained between '10 C. and 200 C.

7. In a process as defined in claim 2 in which the temperature of the liquid bath is maintained between 70 C. and 200 C.

8. In a process for reacting a regenerated cellulose textile material with formaldehyde, the steps comprising impregnating said material with an aqueous solution of formaldehyde and an acid reacting catalyst, drying said impregnated material, and heating the same to reaction temperature by immersion in a hot organic liquid bath which is basic in reaction.

9. In a process for reacting a regenerated cellulose textile materlal with formaldehyde. the steps comprising impregnating said material with an aqueous solution of formaldehyde and an acid reacting catalyst, drying said impregnated material, and heating the same to reaction temperature by immersion in a hot organic liquid steps comprising impregnating said material with an aqueous solution of formaldehyde and an acid reacting catalyst, drying said impregnated material, and heating the same to reaction temperature by immersion in a hot organic liquid bath comprising a sufllcient quantity of a basic amino nitrogen-containing material that the bath is basic in reaction.

11. In a process for reacting a regeneratedcellulose textile material with formaldehyde, the steps comprising impregnating said material with an aqueous solution of formaldehyde and an acid reacting catalyst, drying said impregnated material, and heating the same to reaction temperature by immersion in a hot organic liquid bath comprising a sufllcient quantity of a basic tertiary amine that the bath is basic in reaction.

12. In a process for reacting a regenerated cellulose textile material with formaldelwde, the steps comprising impregnating said material with an aqueous solution of formaldehyde and an acid reacting catalyst, drying said impregnated material, and heating the same to reaction temperature by immersion in a hot organic liquid bath comprising a sufllcient quantity of triethanolamine that the bath is basic in reaction.

13. In a process as defined in claim 8 in which the temperature of the liquid bath is maintained between 70 C. and 200 C.

14. In a process as defined in claim 9 m which the temperature of the liquid bath is maintained between 70 C. and 200 C.

WILLIAM J. BURKE. ROBERT W. MAXWELL. PAUL S. PINKNEY. 

